Contributions of changes in atmospheric circulation and thermodynamic factors to trends in spring gale events in northern China from 1973 to 2020

Surface wind speed (SWS) over China exhibited a decreasing trend before the mid-1990s, referred to as SWS stilling, and an increasing trend thereafter. Northern China is susceptible to dust incidents in spring because of gales. In this study, we investigate the characteristics and causes of spring gale events over northern China. We find that gale events had a decreasing trend during both the SWS stilling and recovery period, reaching -0.68 day/year during the period 1973-2020. Four types of weather systems are associated with gale events, and analysis of all four weather systems indicates that the deep trough in the east of Eurasia is prone to cause gale events. Changes in atmospheric circulation contributed in part to the decrease of gale events, while thermodynamic factors arising from human emissions of greenhouse gases and aerosols, and radiation changes caused by land use change, dominated the decreasing trend of gale events during the last 5 decades.